Method for preparing a nitrile chlorofiber-llzto composite solid electrolyte membrane from waste nitrile chlorofiber material and application thereof

Abstract

The application provides a method for preparing a nitrile chlorofiber-LLZTO composite solid-state electrolyte membrane from waste nitrile chlorofiber material and application thereof, first, pre-recovered waste nitrile chlorofiber is washed and dried; then, the nitrile chlorofiber, LLZTO and LiTFSI are uniformly dispersed in N, N-dimethylformamide solvent to prepare a spinning precursor solution, and an organic-inorganic composite nanofiber membrane (nitrile chlorofiber-LLZTO NFS) is prepared through an electrostatic spinning technology; finally, an organic-inorganic system (PEO / SN) mixed solution is poured on the nitrile chlorofiber-LLZTO NFS through a solution pouring method to obtain a nitrile chlorofiber-LLZTO composite solid-state electrolyte membrane with a double lithium salt system, the material has good tensile flexibility, can be bent and folded, as a solid-state electrolyte of a full solid-state lithium metal battery, exhibits excellent ion transmission performance, and meets the requirements of long-period use.

Description

Technical Field

[0001] The present invention relates to a method for preparing an energy storage system device material, and in particular to a method for preparing an acrylonitrile-LLZTO composite solid electrolyte membrane using waste acrylonitrile material and application thereof, belonging to the technical field of energy storage system device material preparation. Background Art

[0002] The rapid development of the textile industry and fast fashion has resulted in approximately 92 million tons of textile waste generated each year. About 85% of this waste is disposed of through landfills and incineration, which causes serious environmental pollution and waste of resources. However, of the textile waste disposed of in landfills, more than 90% can be reused or recycled. Even after treatment, discarded clothing still has a potential service life of about 70%. Modacrylic is a fiber made by emulsion polymerization of vinyl chloride and acrylonitrile, followed by warm or dry spinning. Its main components are vinyl chloride and acrylonitrile, with a vinyl chloride content usually between 40% and an acrylonitrile content between 60%. This fiber is between chlorofluorocarbon and acrylic fiber, has good heat resistance and flame retardancy, and is elastic, so it is widely used in a variety of application scenarios. Regarding the recycling methods of waste modacrylic, there are currently several options, including physical recovery, chemical recovery, and energy recovery. However, these methods have problems such as low quality, high cost, and environmental pollution. Therefore, it is of great significance to adopt sustainable management methods to carry out simple and green preparation and high-value reuse of waste chlorofluorocarbon.

[0003] Inorganic-polymer composite solid electrolytes are typically prepared by dispersing conductive or non-conductive inorganic nanoparticles in an organic polymer matrix to enhance overall ionic conductivity and impart mechanical flexibility. However, interfacial degradation between the polymer and the lithium anode in composite solid electrolytes can lead to interfacial instability. Therefore, one current research direction is to construct interfacial self-reinforced membranes to promote ion transport and improve the cycle life of lithium metal batteries. Summary of the Invention

[0004] The present invention provides a nylon-LLZTO composite solid electrolyte membrane. The electrolyte membrane is prepared from waste nylon material, has good tensile flexibility, and can be bent and folded. When used as a solid electrolyte material for an all-solid-state lithium metal battery, the membrane has good ion transmission capacity and can meet the requirements of a long-life lithium metal battery.

[0005] The present invention also provides a method for preparing a nylon-LLZTO composite solid electrolyte membrane by using waste nylon material.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A method for preparing a nylon-LLZTO composite solid electrolyte membrane using waste nylon material and its application, the method comprising the following steps:

[0008] S1. Cleaning of waste acrylic fiber

[0009] The dyed or colorless acrylic fiber, yarn or fabric to be recycled (collectively referred to as acrylic) is washed with running water to remove impurities, then immersed in anhydrous ethanol for 12 hours to 15 hours, and vacuum-dried to obtain clean acrylic;

[0010] S2. Preparation of organic-inorganic composite nanofiber membrane

[0011] Adding S1-treated nylon, inorganic ceramic filler LLZTO, and lithium bis(trifluoromethanesulfonyl imide) (LiTFSI) to N,N-dimethylformamide (DMF) solvent and stirring thoroughly at 35-80° C. to obtain a uniformly mixed spinning precursor solution; wherein the weight ratio of nylon to LLZTO is 1:0.02-0.3, and the amount of LiTFSI added accounts for 0.2-3% of the mass of the nylon;

[0012] The spinning precursor solution is electrospun into a nylon / LZTO nanofiber membrane, and then vacuum-dried at 45±5° C. to obtain an organic-inorganic composite nanofiber membrane;

[0013] S3. Preparation of electrolyte solution

[0014] Polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorooxalatoborate (LiDFOB), and succinonitrile (SN) were dried in vacuum within a suitable temperature range and then used.

[0015] PEO, LiTFSI, and LiDFOB were uniformly stirred in an appropriate amount of solvent until completely dissolved, and then SN was added and stirred until uniformly dispersed to obtain a double lithium salt PEO-based electrolyte solution;

[0016] Based on the mass of PEO as 100%, the amount of SN is 10-80%, the amount of LiTFSI is 10%-50%, and the molar ratio of LiDFOB to LiTFSI is 1:18-20.

[0017] S4. Preparation of composite solid electrolyte membrane

[0018] The organic-inorganic composite nanofiber membrane prepared in S2 is placed on a polytetrafluoroethylene mold, and a layer of electrolyte solution prepared in S3 is cast on the surface; after the solvent is completely evaporated, it is vacuum dried at a temperature of 40-50°C to obtain a nitrile-LLZTO composite solid electrolyte membrane of a double lithium salt system.

[0019] Vinyl chloride and acrylonitrile, the primary components of PAN and PVC, are found in chloroacrylic fibers. However, chloroacrylic fibers are relatively inexpensive. The application of PAN and PVC in energy storage devices makes the high-quality utilization of waste chloroacrylic fibers highly feasible. Electrospinning technology, popular for its rapid production speed and ease of operation, holds great potential for producing high-performance materials (such as mechanical properties and ionic conductivity). Therefore, we attempted to combine waste chloroacrylic fibers with energy storage devices through electrospinning.

[0020] The present invention first cleans and dries pre-recovered nylon; then, uniformly disperses nylon, LLZTO, and LiTFSI in an N,N-dimethylformamide solvent; prepares an organic-inorganic composite nanofiber membrane (nylon-LLZTO NFS) by electrospinning technology; and finally, casts an organic-inorganic system (PEO / SN) mixed solution on the nylon-LLZTO NFS by a solution casting method to obtain a nylon-LLZTO composite solid electrolyte membrane. This material can be applied to the energy storage field of flexible lithium-ion batteries.

[0021] This invention recycles waste nylon for high-quality recycling. Using a simple, low-cost electrospinning method with process-controllable equipment, nylon-LLZTO NFS is produced. This creates a 3D nanofiber framework that enhances the mechanical properties and flexibility of the electrolyte. The porous structure of the NFS can be filled with a high-ionic-conductivity PEO-based electrolyte solution. The resulting composite solid-state electrolyte possesses multiple ion channels and exhibits excellent electrochemical properties.

[0022] The nylon, LiTFSI and LiDFOB used in the present invention participate in the formation of a solid electrolyte interface (SEI), forming a multi-component SEI to improve cycle stability and inhibit lithium dendrite growth.

[0023] Preferably, the acrylic fiber in S1 needs to be washed and dried at a temperature of 60-80° C. When preparing the spinning solution, all raw materials must be dried. If the raw materials absorb water, the spinning solution cannot be prepared, spinning cannot be carried out, or the electrochemical properties of the finished product may be affected.

[0024] Preferably, the stirring temperature of the electrospinning precursor solution is 35-80° C. This temperature range allows the chloronitrile to be completely dissolved to obtain a uniform solution.

[0025] Preferably, the weight ratio of nylon to LLZTO is 1:0.05-0.2, and the amount of LiTFSI added is 0.5-1.5% of the weight of nylon. The optimal weight ratio of nylon to LLZTO is 1:0.15.

[0026] Preferably, the electrospinning parameters are: an electrostatic voltage of 11-15 kV, a spinning distance of 9-12 cm, a flow rate of the electrospinning precursor solution of 0.4-0.7 mL / h, and a spinning drum speed of 170-250 rpm.

[0027] Preferably, in S3, the total solute is polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorooxalatoborate (LiDFOB), and succinonitrile (SN); based on the mass of PEO as 100%, the amount of SN is 20-60%. More preferably, based on the mass of PEO as 100%, the amount of SN is 40-60%.

[0028] The preferred LiTFSI dosage is 25%-40%, with an optimal concentration of 33%. The molar ratio of LiDFOB to LiTFSI is 1:19. Due to the high dissociation capacity of LiTFSI and the excellent film-forming properties of LiDFOB, these two lithium salts, combined with PEO and SN, offer optimal casting solutions.

[0029] Preferably, the solvent in S3 is a PEO-soluble solvent such as acetonitrile or N,N-dimethylformamide, and the stirring time when PEO and conductive lithium salt are mixed is 12-18 hours; the drying time of the composite solid electrolyte membrane in S4 is 7-12 hours.

[0030] Preferably, the total thickness of the composite solid electrolyte membrane is 90 μm-110 μm.

[0031] A chloronitrile-LLZTO composite solid electrolyte membrane prepared by the preparation method of the present invention.

[0032] A use of the nylon-LLZTO composite solid electrolyte membrane of the present invention in preparing a solid electrolyte or a solid-state lithium-ion battery with flame retardancy.

[0033] The method of the present invention is easy to implement and can be scalably produced. The resulting organic-inorganic composite nanofiber membrane can form a three-dimensional ion-conducting path. The resulting nitrile-LLZTO composite solid electrolyte membrane with a dual lithium salt system has excellent tensile flexibility and can be bent and folded. When used as a solid-state electrolyte material for all-solid-state lithium metal batteries, it has excellent ion transport capabilities and can meet the requirements of long-life lithium metal batteries.

[0034] To achieve composite solid-state electrolytes with high ionic conductivity and excellent mechanical flexibility, an organic-inorganic composite nanofiber membrane (LLZTO NFS) can be prepared via electrospinning and then compounded with a high-ionic-conductivity PEO / SN electrolyte solution to create a nylon-LLZTO composite solid-state electrolyte membrane. The continuous 3D ion-conducting pathways of the organic-inorganic composite nanofiber membrane enhance the overall ion conductivity of the solid-state electrolyte, while the PEO polymer matrix imparts mechanical flexibility. Appropriate additives can disrupt the PEO order, reduce crystallinity, enhance polymer chain dynamics, improve ionic conductivity, and enhance electrode-electrolyte interfacial compatibility. Furthermore, uniform lithium deposition is achieved during the charge and discharge process of lithium metal batteries, enabling stable ion transport. This composite solid-state electrolyte, combining electrochemical performance with mechanical flexibility, holds great promise for application in solid-state batteries.

[0035] Recycled chloronitrile is usually blended with other fiber materials (such as cotton, wool, and PET fibers) and contains dye materials, which may hinder their recycling. During the dissolution process, the blended fibers can be removed by filtration. The dye does not need to be further processed, which greatly reduces the difficulty of recycling. First of all, the dyes used in these fabrics only account for a maximum of 3% of the fabric mass, and most of the dyes used are azo dyes, which contain high nitrogen and can serve as a source of N in the electrolyte. In addition, the crystallinity of chloronitrile is reduced after high-temperature dyeing, which is conducive to the improvement of electrochemical performance.

[0036] In summary, the method of the present invention has the following characteristics:

[0037] 1. Acrylic can be recycled for high quality, whether dyed or not, including acrylic fiber, yarn and fabric;

[0038] 2. The present invention adopts electrospinning method, which is simple to operate, and the reaction conditions are easy to control and implement, and is suitable for large-scale production;

[0039] 3. The electrospinning method produces a continuous 3D ion-conducting path and ion channel in the nylon-LLZTO nanofiber membrane, significantly improving the mechanical properties and thermal stability of the nylon-LLZTO solid electrolyte.

[0040] 4. LLZTO organic filler improves the ionic conductivity of the electrolyte and promotes the uniform deposition of lithium ions. The dual lithium salt system forms a stable SEI layer at the interface between the electrolyte and the electrode, effectively inhibiting the side reaction between SN and the lithium negative electrode, which is beneficial to improving the ion transmission efficiency;

[0041] 5. The prepared nylon-LLZTO composite solid electrolyte membrane can be used in lithium metal batteries. The LiCl generated by the nylon PVC segment in the SEI layer is more stable and efficient than LiF, significantly improving the stability of the battery interface and extending the battery cycle life. The flame retardant properties of nylon make the nanofiber membrane and electrolyte prepared using it as a polymer raw material through the process of the present invention heat-resistant.

[0042] 6. The prepared nylon-LLZTO composite solid electrolyte membrane has practical application value in flexible soft-pack batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a scanning electron microscope (SEM) photograph of the surface of the nylon-LLZTO nanofiber membrane prepared in Example 1;

[0044] Figure 2 is a scanning electron microscope (SEM) photograph of the nylon-LLZTO composite solid electrolyte membrane prepared in Example 1;

[0045] Figure 3 The polarization curve (left) and the interface resistance diagram before and after polarization (right) of the Li / solid electrolyte / Li symmetric cell of the nylon-LLZTO composite solid electrolyte membrane prepared in Example 1 are shown;

[0046] Figure 4 This is a test chart of the cycling stability of a Li / solid electrolyte / Li symmetric battery of the nylon-LLZTO composite solid electrolyte membrane prepared in Example 1;

[0047] Figure 5 The electrochemical impedance spectroscopy (EIS) graph (left) and an enlarged graph (right) of the impedance graph of a stainless steel / solid electrolyte / stainless steel symmetrical cell with a nylon-LLZTO composite solid electrolyte membrane prepared in Example 1 at different temperatures are shown;

[0048] Figure 6 This is the XPS test spectrum of the surface of the nylon-LLZTO composite solid electrolyte membrane before and after cycling;

[0049] Figure 7 (a) The polarization curve of the Li / solid electrolyte / Li symmetrical cell of the nylon-LLZTO composite solid electrolyte membrane prepared in Comparative Example 1 and (b) the interface resistance diagram before and after polarization;

[0050] Figure 8 This is a test chart of the cycling stability of a Li / solid electrolyte / Li symmetric battery of the nylon-LLZTO composite solid electrolyte membrane prepared in Comparative Example 1;

[0051] Figure 9The polarization curve (left) and the interface resistance diagram before and after polarization (right) of the Li / solid electrolyte / Li symmetric cell of the nylon-LLZTO composite solid electrolyte membrane prepared in Comparative Example 2 are shown;

[0052] Figure 10 This is a test chart of the cycling stability of a Li / solid electrolyte / Li symmetric battery of the nylon-LLZTO composite solid electrolyte membrane prepared in Comparative Example 2;

[0053] Figure 11 This is the Arrhenius plot measured after adding different LLZTO contents to the nylon-LLZTO composite solid electrolyte membrane prepared in Comparative Example 3;

[0054] Figure 12 This is the Arrhenius plot measured for the chloronitrile-LLZTO composite solid electrolyte membrane prepared by adding different mass fractions of SN to the PEO-SN casting solution of Comparative Example 4;

[0055] Figure 13 These are the combustion test diagrams of nanofiber membranes made of PAN powder and chloronitrile respectively;

[0056] Figure 14 This is a microcalorimeter test of the composite solid electrolyte made of PAN powder and chloronitrile, and the solid electrolyte of Comparative Example 1;

[0057] Figure 15 This is a diagram of the preparation process of the colored nylon-LLZTO composite solid electrolyte membrane prepared in the application example;

[0058] Figure 16 This is an application diagram of the colored nylon-LLZTO composite solid electrolyte membrane prepared in the application example to prepare soft-pack batteries;

[0059] Figure 17 This is a diagram of the application of the colored nylon-LLZTO composite solid electrolyte membrane prepared in the application example to prepare soft-pack batteries at low temperatures. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described in detail below through specific examples. It should be understood that the implementation of the present invention is not limited to the following examples, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0061] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0062] Unless otherwise specified, the reagents used in the following examples can be purchased from conventional biochemical reagent stores.

[0063] Example 1 (Best Case)

[0064] A method for preparing a nylon-LLZTO composite solid electrolyte membrane using waste nylon material, the specific steps of the method are as follows:

[0065] (1) Cleaning of waste acrylic fiber: Wash the pre-recovered waste acrylic fiber under running water for 10 minutes, then add an appropriate amount of ethanol (to submerge the acrylic fiber) and soak for 10 hours. After taking it out, place it in a vacuum oven for drying.

[0066] (2) Preparation of organic-inorganic composite nanofiber membrane: Weigh 1 g of cleaned nylon, 0.15 g of LLZTO, and 0.1 g of LiTFSI and dissolve them in 5 g of N,N-dimethylformamide solvent and stir them evenly at 50 °C to obtain an electrospinning precursor solution; under the spinning conditions of an electrostatic voltage of 13 kV, a spinning distance of 9 cm, a spinning solution flow rate of 0.6 mL / h, and a drum speed of 200 rpm, the precursor solution is spun into a nanofiber membrane, and then vacuum-dried at 50 °C to evaporate the residual liquid, taken out and placed in an argon-filled glove box for standby use, to obtain an organic-inorganic composite nanofiber membrane (nylon-LLZTO NFS);

[0067] (3) Preparation of electrolyte solution: First, polyethylene oxide (PEO), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium difluorooxalatoborate (LiDFOB), and SN were vacuum dried at 40°C for later use; then, PEO and LiTFSI were dissolved in acetonitrile at a molar ratio of EO:Li=20:1, the molar ratio of LiDFOB to LiTFSI was 1:19, and SN accounted for 40% of the mass of PEO; finally, the mixture was stirred at room temperature for 15 h to form a uniform mixed solution, thereby obtaining the electrolyte solution of the PEO / SN system.

[0068] (4) Preparation of a composite solid electrolyte membrane: First, the PEO / SN system electrolyte solution in step (3) was drawn with a syringe; then, the organic-inorganic composite nanofiber membrane (acrylonitrile-LLZTO NFS) obtained in step (2) was placed on a polytetrafluoroethylene mold, and a layer of the PEO / SN system electrolyte solution was poured until it was completely permeated; finally, after the acetonitrile in the PEO / SN system electrolyte solution was completely volatilized, the acrylonitrile-LLZTO composite solid electrolyte membrane was removed and vacuum dried at 50°C for 10 hours to obtain the final composite solid electrolyte. The total thickness of the composite solid electrolyte membrane was controlled to be 90-110 μm.

[0069] The prepared acrylic fiber-LLZTO NFS has a three-dimensional multi-porous structure ( Figure 1) can be filled with PEO / SN electrolyte solution with good fluidity. After casting, the acrylic fiber-LLZTO SPE has a smooth surface without protrusions ( Figure 2 ), achieving good contact between the electrolyte and the Li metal, and promoting the transport of lithium ions at the interface; the polarization test curve of the prepared nitrile-LLZTO SPE Li / solid electrolyte / Li symmetric battery is shown in Figure 3 , the ion mobility reaches 0.84 at 50℃; and during the charge and discharge process, after >2500h, 100μAcm -2 The Li / solid electrolyte / Li symmetric cell can still operate stably under the current density of electroplating / stripping cycles without significant increase in polarization voltage ( Figure 4 The electrochemical impedance spectroscopy (EIS) of the stainless steel / solid electrolyte / stainless steel battery of the prepared acrylic-LLZTO SPE is shown in FIG. Figure 5 Calculated ionic conductivity at 30°C is 1.7x10 -3 S cm -1 , which improves the electrochemical performance of solid-state lithium metal batteries.

[0070] X-ray photoelectron spectroscopy (XPS) was further used to characterize the composition of SEI. Figure 6 The XPS spectra of the initial electrolyte and the electrolyte surface after cycling in a lithium symmetric battery were compared. New peaks appearing at 684 eV for F1s and 530 eV for O1s after cycling belong to the formed LiF and LiOH, respectively. This suggests that both LiTFSI and LiDFOB decomposed on the lithium surface during cycling to form an SEI layer. The electrolyte before cycling had four distinct C1 2p peaks, indicating that Cl existed in the form of LiCl and C-Cl bonds. After cycling, the main Cl presence on the electrolyte surface was LiCl, demonstrating that the organic chlorine in chloronitrile participates in the formation of the SEI to form a metal chloride compound (LiCl) during cycling. The in situ formed SEI layer between the electrolyte and lithium metal is sufficiently stable to inhibit the growth of lithium dendrites and prevent adverse reactions between SN and lithium metal.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that:

[0073] In step (2), LLZTO is not added when preparing the spinning solution to prepare chloronitrile NFS.

[0074] The polarization test curve of the prepared LLZTO-free nylon SPE Li / solid electrolyte / Li symmetric battery is shown in Figure 7 , the ion mobility at 50°C is only 0.63, and the ion transmission capacity is worse than that of Example 1 ( Figure 8 ).

[0075] Comparative Example 2

[0076] The difference from Example 1 is that:

[0077] Steps (1) and (2) were omitted, and the PEO / SN electrolyte solution prepared in step (3) was cast on a polytetrafluoroethylene mold. After the acetonitrile in the PEO / SN electrolyte solution was completely volatilized, the PEO / SN SPE was removed and vacuum dried at 50° C. for 24 h to obtain the solid electrolyte of Comparative Example 2. The total thickness of the solid electrolyte membrane was controlled to be 90-110 μm.

[0078] The ion mobility of the prepared PEO / SN Li / solid electrolyte / Li symmetric battery at 50°C was only 0.43 ( Figure 9 ), the ion transmission capacity is poor. After about 150h, a short circuit occurs ( Figure 10 ).

[0079] Comparative Example 3

[0080] The difference from Example 1 is that:

[0081] In step (2), the LLZTO content was changed to 0, 0.05, 0.10, 0.15 and 0.20 g (the figure numbers in the figure are abbreviated, such as 0.05 is abbreviated as 5, and 0.10 is abbreviated as 10) to prepare different chloronitrile-LLZTO NFS.

[0082] The ionic conductivity of nylon-LLZTO SPE with different LLZTO contents was compared ( Figure 11 As the LLZTO content increases, the ionic conductivity of the stainless steel / solid electrolyte / stainless steel symmetric cell also increases. However, when the LLZTO content reaches 0.2g, the ionic conductivity of the stainless steel / solid electrolyte / stainless steel symmetric cell decreases. This may be because excessive ceramic filler causes aggregation and hinders ion transport. Therefore, the optimal weight ratio of chloronitrile to LLZTO is 1:0.15.

[0083] Comparative Example 4

[0084] The difference from Example 1 is that:

[0085] Taking the mass of PEO as 100%, the content of SN in step (3) was changed to 0, 20, 40, 60 and 80% to prepare different PEO / SN casting solutions.

[0086] The ionic conductivity of chloronitrile-LLZTO CSE with different SN contents was compared ( Figure 12). With the increase of SN content, the ionic conductivity increased significantly. However, when the SN addition increased from 40wt% to 60wt% of PEO, the ionic conductivity did not increase significantly. After the SN addition continued to increase to 80wt%, the ionic conductivity decreased because the excessive SN filler caused the PEO amorphous phase to decrease and form discontinuous Li + Therefore, it is believed that the optimal amount of SN added is 40-60wt% of PEO.

[0087] Comparative Example 5

[0088] The difference from Example 1 is that:

[0089] The PAN-LLZTO NFs were prepared by the same process by replacing PAN powder with acrylic chloronitrile, and then PLCSE was obtained by pouring PN casting solution.

[0090] The flame retardant properties of different fiber membrane materials were tested. The results showed that ( Figure 13 WML-based NFs (WML NFs) rapidly contracted under flame and extinguished themselves, no longer burning or smoldering. This is because the chlorine in the WML NFs releases HCl during combustion, effectively suppressing further combustion. The safety performance of the electrolyte was further tested using a microcalorimeter (MCC). Figure 14 The peak heat release rate (PHRR) and heat release amount (THR) of different electrolytes are shown. PAN is a flammable polymer with low thermal stability. Even though Example 5: PAN-LLZTO CSE (PLCSE) prepared by the process of the present invention still has a high PHRR (241.531 W / g), the PHRR (119.816 W / g) of the WML CSE prepared in Example 1 is only half of that of the PL CSE. It is worth noting that even Comparative Example 1 (WM SPE) without the addition of LLZTO has a lower PHRR (201.144 W / g). Similarly, the THR of WML CSE and WM SPE is reduced from 14 of PLCSE to 10.7 KJ / g and 13.5 KJ / g. The above results show that the electrolyte prepared using waste nylon copolymerized with PAN and PVC has better heat resistance than PAN, and the successful addition of LLZTO further improves the thermal stability of the composite solid electrolyte. These results demonstrate that the use of acrylic fiber provides a safer working environment for lithium-ion batteries than PAN (or acrylic fiber prepared from PAN).

[0091] Application example: Packaging of soft-pack batteries

[0092] The difference from Example 1 is that:

[0093] In step (1), colorless, red, yellow and blue acrylic fibers are washed and dried respectively for later use.

[0094] In step (2), 1 g of nylon was weighed, wherein the weight ratio of colorless nylon, red nylon, yellow nylon, and blue nylon was 1:3:3:3. Dyed nylon-LLZTO NFS was prepared for the subsequent step of preparing dyed nylon-LLZTO SPE.

[0095] Prepare a LiFePO4 coated positive electrode (the size can be larger than the lithium sheet), and cut a 3×3cm lithium sheet in a glove box, and then prepare two electrodes. By heating the two pole ears in the electrode, the electrode is connected to the dyed nylon-LLZTO SPE (preparation diagram as shown in the figure) Figure 15 ) are bonded and encapsulated together in aluminum foil (heating times: 3-5 times). It is particularly important to ensure that the vacuum in the aluminum foil is completely evacuated during the packaging process (vacuuming times: 5-7 times) to prevent the lithium sheet from oxidizing. In order to demonstrate the cycle stability of the dyed nitrile-LLZTO composite solid electrolyte membrane provided by the present invention in the soft-pack battery, the two pole pieces are first connected to the positive and negative electrodes of the LED lamp respectively, thereby lighting it up, and its safety performance is tested in the soft pack. The on-site photos are as follows: Figure 16 As shown, the brightness of the LED light is not affected, proving that the composite solid electrolyte has good cycle stability. The soft pack battery is placed in an ice bag environment and can still power the LED light after being left to stand. ( Figure 17 )

[0096] The above experiments fully prove that the prepared nylon-LLZTO composite solid electrolyte membrane can greatly improve the electrochemical performance of solid-state lithium metal batteries and can be actually used in the preparation of flexible solid-state lithium batteries.

[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0098] The above is a detailed introduction to the method for preparing a nylon-LLZTO composite solid electrolyte membrane using waste nylon material provided by the present invention and its application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core concept. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a nylon-LLZTO composite solid electrolyte membrane using waste nylon material, characterized in that The method comprises the following steps: S1. Cleaning of waste acrylic fiber The dyed or colorless acrylic fiber, yarn or fabric to be recycled is washed with running water to remove impurities, then immersed in anhydrous ethanol for 12 hours to 15 hours, and vacuum-dried to obtain clean acrylic fiber; S2. Preparation of organic-inorganic composite nanofiber membrane Adding S1-treated nylon, inorganic ceramic filler LLZTO, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to N,N-dimethylformamide (DMF) solvent and stirring thoroughly at 35-80°C to obtain a uniformly mixed spinning precursor solution; wherein the weight ratio of nylon to LLZTO is 1:0.02-0.3, and the amount of LiTFSI added accounts for 0.2-3% of the mass of the nylon; The spinning precursor solution is electrospun into a nylon / LLZTO nanofiber membrane, which is then vacuum-dried at 45±5° C. to obtain an organic-inorganic composite nanofiber membrane; S3. Preparation of electrolyte solution Polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorooxalatoborate (LiDFOB), and succinonitrile (SN) were vacuum dried within a suitable temperature range and then used. PEO, LiTFSI, and LiDFOB were uniformly stirred in an appropriate amount of solvent until completely dissolved, and then SN was added and stirred until uniformly dispersed to obtain a double lithium salt PEO-based electrolyte solution; Based on the mass of PEO as 100%, the amount of SN is 10-80%, the amount of LiTFSI is 10%-50%, and the molar ratio of LiDFOB to LiTFSI is 1:18-20. S4. Preparation of composite solid electrolyte membrane The organic-inorganic composite nanofiber membrane prepared in S2 is placed on a polytetrafluoroethylene mold, and a layer of electrolyte solution prepared in S3 is cast on the surface; after the solvent is completely evaporated, it is vacuum dried at a temperature of 40-50°C to obtain a nitrile-LLZTO composite solid electrolyte membrane of a dual lithium salt system.

2. The method according to claim 1, wherein: The acrylic fiber in S1 needs to be washed and dried at a drying temperature of 60-80°C.

3. The method according to claim 1, wherein: The weight ratio of chloroacrylic fiber to LLZTO is 1:0.05-0.2, and the addition amount of LiTFSI is 0.5-1.5% of the mass of chloroacrylic fiber.

4. The method according to claim 1, wherein: The electrospinning parameters are: static voltage 9-16 kV, spinning distance 8-13 cm, electrospinning precursor flow rate 0.2-0.9 mL / h, and spinning drum speed 150-280 rpm.

5. The method according to claim 1, wherein: The total thickness of the composite solid electrolyte membrane is 90 μm-110 μm.

6. The method according to claim 1, wherein: In S3, all solutes are polyethylene oxide (PEO), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluorooxalatoborate (LiDFOB) and succinonitrile; based on the mass of PEO as 100%, the amount of SN is 20-60%.

7. The method according to claim 1, wherein: In S3, the amount of LiTFSI is 25%-40%; the molar ratio of LiDFOB to LiTFSI is 1:

19.

8. The method according to claim 1, wherein: The solvent in S3 is acetonitrile or N,N-dimethylformamide, and the stirring time when PEO, LiTFSI and LiDFOB are mixed is 12-18 h; the drying time of the composite solid electrolyte membrane in S4 is 7-12 h.

9. A chloronitrile-LLZTO composite solid electrolyte membrane prepared by the method according to claim 1.

10. Use of the nylon-LLZTO composite solid electrolyte membrane according to claim 1 in preparing a solid electrolyte or a solid-state lithium-ion battery with flame retardancy.

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